1. Field of the Invention
The present invention relates generally to construction materials and methods, and more particularly, is concerned with a concrete anchoring device and method of use to provide an inexpensive, and potentially recoverable, concrete anchor for a standard nut and bolt, or the like.
2. Description of the Prior Art
Existing concrete anchoring devices and methods of use include specially manufactured bolts having integrally attached anchoring devices that cooperate with the bolts to provide a substantially permanent anchoring attachment of the bolts and their anchoring devices within prepared receiving holes in the concrete. FIGS. 1 and 2 (Prior Art) illustrate two of the most common concrete anchoring devices of the prior art.
The device illustrated in FIG. 1 includes a specialty bolt 10 that is threadingly received within one end of a fitting 12 that has been furnished with a through-bore 14 that tapers down to a diameter smaller than that of the bolt 10 at its other, unthreaded end 16. At end 16 of fitting 12, the fitting has been cut into quarter sections 18. Thus, when the combined bolt 10 and fitting 12 are placed into a pre-drilled concrete hole selectively sized to be just slightly larger than the diameter of fitting 12, advancing bolt 12 into the threaded end of fitting 12 by clockwise rotation of bolt head 20 will force bolt 10 through the tapered through bore 14 toward the unthreaded end 16. This will force quarter sections 18 outwardly and into contact with the walls of the pre-drilled concrete hole. The frictional forces thus created between quarter sections 18 and the walls of the pre-drilled concrete hole anchor fitting 12, and bolt 10, within the pre-drilled concrete hole.
The device illustrated in FIG. 2 includes a specialty rod 30 that has been threaded and provided with a nut 32 at one end. At the opposite end 36, the rod has been milled to provide a conically tapered section 36 that begins at end 36 and runs toward the opposite threaded end. An expandable sleeve 38 has been fitted over the portion of the conically tapered section 36 that is closest to the threaded end of rod 30. On opposite sides of expandable sleeve 38 are a pair of integral protrusions 40 (only one shown) that protrude outwardly beyond the diameter of rod 30. When the combined rod 30 and expandable sleeve 38 are placed into a pre-drilled concrete hole selectively sized to snugly receive the protrusions 40 on expandable sleeve 38, advancing nut 32 by clockwise rotation toward end 36 of rod 30 against the concrete surface surrounding the pre-drilled concrete hole will begin forcing rod 30 out of the pre-drilled concrete hole. Expandable sleeve 38 will remain fairly stationary, however, due to the frictional forces between protrusions 40 and the pre-drilled concrete hole. As end 34 moves up the pre-drilled concrete hole, expandable sleeve 38 will be forced outwardly by the increasing diameter of the conically tapered section 36, increasing the frictional forces upon protrusions 40 until rod 30 can no longer be advanced out of the pre-drilled concrete hole. The frictional forces thus created between protrusions 40 and the walls of the pre-drilled concrete hole firmly anchor rod 40 within the pre-drilled concrete hole.
Both of the prior art devices illustrated in FIGS. 1 and 2 are relatively expensive, and their methods of use render them useful for only a single application. Also, they are not adjustable to accommodate varyingly sized pre-drilled concrete holes. A given anchor of the type illustrated in either FIG. 1 or 2 would be sized to fit only pre-drilled concrete holes of a given diameter, within limited tolerances. Furthermore, when the device of FIG. 1 had served its purpose, bolt 10 would be backed out of fitting 12, and the pre-drilled concrete hole would be filled with concrete. In the case of the device of FIG. 2, nut 32 would be backed off and the rod 30 would be driven down until it was wholly within the pre-drilled concrete hole, which are always drilled deeper than the length of the anchoring device to be used, and the pre-drilled concrete hole would be filled with concrete. In each case, the essential elements of the anchoring devices would be irretrievably lost.